Flow over a cylinder

AIM: Simulate the flow over a cylinder.

INTRODUCTIONS :

• Calculate the baseline case Reynolds number.
  • Re = ρ*U_inlet*D/μ
  • D = cylinder diameter
  • mu = dynamic viscosity
  • ρ = density
• Run a baseline simulation and then calculate the Reynolds number. Then increase the Reynolds number by a factor of 20%, 40%, and 100% then run the transient flow simulation.

Air is working fluid in this project.

At 15°C

Air has a density of approximately 1.225 kg/m³ (or 0.00237 slug/ft³)

Air has a Dynamic viscosity of approximately 1.81x10^-5 kg/ms

CALCULATIONS:

Velocity: At, Re = 120

U_inlet = (Re*μ)/(ρ*D)

=(120*1.225)/(.01813*0.04)

V = 0.0443 m/s

Time: At , V = 0.0443 m/s

Time = Length of domain / Velocity

= 0.05/0.0443 (Domain length = 0.05m)

T = 1.13 Sec

CASE 1:

Re=120

Velocity : Here we can see the velocity is between 0 to 0.055m/s.

Pressure :

Here I'm taking laminar flow due to Reynold number and velocity is also very less so in the graph it's not showing anything, but if im increasing velocity then it's showing properly

CASE 2:

Re = 140

Velocity: Here we can see the velocity is between 0 to 0.065m/s.

Pressuer: Here I'm taking laminar flow due to Reynold number and velocity is also very less so in the graph it's not showing anything, but if im increasing velocity then it's showing properly.

CASE 3:

Re 200

Here we can see velocity between 0 to 0.087m/s.

Pressure :

Here I'm taking laminar flow due to Reynold number and velocity is also very less so in the graph it's not showing anything, but if im increasing velocity then it's showing properly

RESULT & CONCLUSION:

As we increase the Reynolds number the velocity of external air flow increases. If we look at the pressre plot we observe that there is negligible change. If we compare velocity plot for 1st and 2nd case that we observe both are similar ways. But we can see significant difference velocity plot change for 3rd case.